Cisco IAD2430 - Manual (Page 36)

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Cisco IAD2430 Series Integrated Access Devices Hardware Installation Guide
OL-4234-06
Chapter 2 Planning Your Installation
Interference Considerations
T1/E1-PBX Digital Voice Port Maximum Distances
Table 2-5 shows the maximum distances between the digital voice port of a Cisco IAD and a digital
PBX.
FXS Analog Voice Port Maximum Distance
The maximum distance for a Foreign Exchange System (FXS) is established by a total allowable loop
resistance, including off-hook phone or terminal equipment, of 600 ohm. The maximum distance is
100 meters away from the system as a limitation of Ethernet.
FXO Analog Voice Port Maximum Distance
The maximum distance is determined by the distance between the PBX or other equipment that provides
battery and the connection to the FXO voice port.
Interference Considerations
When you run cables for any significant distance in an electromagnetic field, interference can occur
between the electromagnetic field and the signals on the cables. This has two implications for
installating terminal plant cabling:
• Unshielded plant cabling can emit radio interference.
• Strong electromagnetic interference (EMI), especially that caused by lightning or radio transmitters,
can destroy the EIA/TIA-232 drivers and receivers in the Cisco IAD.
If you use twisted-pair cables with a good distribution of grounding conductors in your plant cabling,
emitted radio interference is unlikely.
If you have cables that exceed the recommended distances, or if you have cables that pass between
buildings, give special consideration to the effect of lightning strikes or ground loops. If your site has
these characteristics, consult experts in lightning suppression and shielding. The electromagnetic pulse
caused by lightning or other high-energy phenomena can easily couple enough energy into unshielded
conductors to destroy electronic devices.
Without pulse meters and other special equipment, most data centers cannot resolve the infrequent but
potentially catastrophic problems just described. Take precautions to avoid these problems by providing
a properly grounded and shielded environment and by installing electrical surge suppression.
If you remove any module, you must either install a module in its place or install a cover plate over the
opening. All module openings must be either occupied or covered to prevent electromagnetic
interference.
For advice on the prevention of electromagnetic interference, consult experts in radio frequency
interference (RFI).
Table 2-5 Digital Voice Port Speed and Distance Limitations
Signal Rate Distance (Feet) Distance (Meters)
T1/E1 (CSU) 3000 915